The invention relates to an installation for treating, in particular for painting, objects, especially vehicle bodies, comprising
a) at least one bath containing a treatment liquid, in particular a paint, in which the objects are to be immersed;
b) a conveying device by means of which the objects can be transported in a continuous or intermittent translation movement through the installation;
c) a plurality of immersion devices that in each case carry an object on a supporting structure joined via a connecting structure to the conveying device and that are able to immerse the said object in the bath.
Such an installation is described in DE 196 41 048 C2. In this installation the immersion devices are designed so that the objects to be treated, in the illustrated embodiment car bodies to be painted, are immersed in the baths by a combination of the translation movement and a rotational movement about an axis aligned perpendicular to the transportation direction and are then removed from the baths. The connecting structures of these immersion devices are in this connection rigid holding frames comprising, in the normal position in the lower and middle regions, a single rotational axis for the rotational movement. The rationale of this arrangement is to be able to immerse completely in the baths, in a relatively short path of the translation movement, the objects to be treated, with the result that the front walls of the baths may be steep and the baths overall may be short. The disadvantage is that the objects to be treated have to be turned completely upside down. This requires very complicated holding frames and large forces in the case of objects of considerable weight. When the objects to be treated are vehicle bodies their movable parts, for example doors, luggage boots and bonnets, have to be secured so they cannot open. Furthermore these known immersion devices permit only a single kinematics of the immersion movement, specifically just the rotational movement, which is not ideal for many objects that have unfavourable geometries in this regard.
The object of the present invention is to modify and improve an installation of the type mentioned in the introduction, so that by using substantially identically short baths a rotation of the objects to be treated by 180xc2x0 is not necessary and the kinematics of the immersion procedure can optionally be varied.
This object is achieved according to the invention if
d) the connecting structure comprises at least one pivoting arm that is coupled to the conveying device about a first axis, and a drive device associated with the pivoting arm by means of which the said pivoting arm can be swivelled;
e) the supporting structure is swivellably coupled to the pivoting arm about a second axis that is spaced from the first axis, and
f) a drive device is provided by means of which the supporting structure can be swivelled about the second axis relative to the pivoting arm.
According to the invention a double swivelling possibility is thus provided within the connecting structure included in each immersion device: on the one hand the pivoting arm itself swivels relative to the conveying device, and on the other hand the supporting structure swivels relative to the pivoting arm. Both swivelling movements may be performed independently of one another by in each case a separate drive device. By suitably coordinating the two drive devices it can also be ensured that the object retains its orientation relative to the horizontal or vertical during a swivelling movement of the pivoting arm. The installation according to the invention enjoys particular flexibility if the two pivoting degrees of freedom are coupled with a suitable linear movement of the conveying system.
Conveniently the drive device for the swivelling movement of the supporting structure relative to the pivoting arm should be arranged at a position that does not dip into the bath when the pivoting arm is swivelled, and should be connected to the said supporting structure via a mechanical adjustment device. The treatment liquids within the baths, including paints, may be so aggressive that the drive device should not be exposed to these treatment liquids. The adjustment devices on the other hand may be made to be so resistant that they do not suffer any damage due to the treatment liquid.
It is particularly preferred in this regard if the adjustment device comprises a track arrangement. Not only can considerable forces be transmitted via such a track arrangement, but the latter operates robustly and reliably also in an environment in which substances may form deposits thereon. Deposits that have become encrusted may be removed without any difficulty by such a track arrangement.
It is particularly advantageous if the adjustment device comprises two bars that are on the one hand coupled to a part rigidly connected to the supporting structure and on the other hand are coupled to a part rigidly connected to the output shaft of the drive device, so that they never simultaneously reach a dead point. In this way pivoting angles that are greater than 180xc2x0 can be produced without any problem.
In principle the mechanical adjustment device may however also comprise a conventional chain system.
An advantageous embodiment of the invention is characterised in that the output shaft of the drive device of the pivoting arm is hollow and the output shaft of the drive device for the swivelling movement of the supporting structure passes coaxially through the output shaft of the drive device of the pivoting arm. This type of structure is particularly economical as regards space.
The pivoting arm conveniently carries a counterbalance weight so that the torque required to swivel the pivoting arm can be kept very small.
A similar objective is pursued in the design of the invention in which the pivoting arm co-operates with an energy storage device that is able to store in the meantime energy released in the reverse movement of the end of the pivoting arm connected to the supporting structure, in order to give back this energy during the forward movement of the pivoting arm.